Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
1) \(\frac{2}{3}+x=-\frac{4}{5}\)
\(x=\left(-\frac{4}{5}\right)-\frac{2}{3}\)
\(x=-1\frac{7}{15}\)
Vậy \(x=-1\frac{7}{15}\)
2) \(\frac{2}{5}-x=-\frac{1}{3}\)
\(x=\frac{2}{5}-\left(-\frac{1}{3}\right)\)
\(x=\frac{11}{15}\)
Vậy \(x=\frac{11}{15}\)
3) \(1-\frac{x}{3}=1\frac{1}{2}\)
\(\frac{x}{3}=1-1\frac{1}{2}\)
\(\frac{x}{3}=-\frac{1}{2}\)
\(\Rightarrow x=\frac{\left(-1\right)\cdot3}{2}\)
\(x=-1\frac{1}{2}\)
4) \(1-\left(\frac{2x}{3}+2\right)=-1\)
\(\frac{2x}{3}+2=1-\left(-1\right)\)
\(\frac{2x}{3}+2=2\)
\(\frac{2x}{3}=2-2\)
\(\frac{2x}{3}=0\)
\(\Rightarrow x=0\)
Vậy \(x=0\)
1. \(\frac{25}{100}x+x-\frac{1}{5}x=\frac{1}{5}\)
\(\Leftrightarrow\frac{1}{4}x+x-\frac{1}{5}x=\frac{1}{5}\)
\(\Leftrightarrow\left(\frac{1}{4}+1-\frac{1}{5}\right)x=\frac{1}{5}\)
\(\Leftrightarrow\frac{21}{20}x=\frac{1}{5}\)
\(\Leftrightarrow x=\frac{1}{5}:\frac{21}{20}\)
\(\Leftrightarrow x=\frac{4}{21}\)
Mấy câu trên dễ , bạn có thể tự làm được
Chứng minh \(\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+\frac{1}{5^2}+...+\frac{1}{10^2}< 1\)
Đặt \(A=\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+\frac{1}{5^2}+...+\frac{1}{10^2}\)
Ta có : \(\frac{1}{2^2}=\frac{1}{2\cdot2}< \frac{1}{1\cdot2}\)
\(\frac{1}{3^2}=\frac{1}{3\cdot3}< \frac{1}{2\cdot3}\)
\(\frac{1}{4^2}=\frac{1}{4\cdot4}< \frac{1}{3\cdot4}\)
...
\(\frac{1}{10^2}=\frac{1}{10\cdot10}< \frac{1}{9\cdot10}\)
=> \(A=\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+\frac{1}{5^2}+...+\frac{1}{10^2}< \frac{1}{1\cdot2}+\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+...+\frac{1}{9\cdot10}\)
=> \(A=\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+\frac{1}{5^2}+...+\frac{1}{10^2}< \frac{1}{1}-\frac{1}{10}\)
=> \(A=\frac{1}{2^2}+\frac{1}{3^2}+\frac{1}{4^2}+\frac{1}{5^2}+...+\frac{1}{10^2}< \frac{9}{10}\)
Lại có : \(\frac{9}{10}< 1\)
=> \(A< \frac{9}{10}< 1\)
=> \(A< 1\left(đpcm\right)\)
\(=-2.\frac{2}{3}.\frac{1}{3}:\left(\frac{-1}{6}+0,5\right)-\left(-2009^0\right)-\left(-2\right)^2\)
\(=\frac{4}{3}.\frac{1}{3}:\left(\frac{-1}{6}+\frac{1}{2}\right)-1.4\)
\(=\frac{4}{3}.\frac{1}{3}+4\)
\(=4+4\)
\(=8\)
giúp mik nha chiều này 6:00 mik nộp rồi
ai nhanh mik sẽ k cho 3 k
\(2\frac{3}{5}x-\frac{1}{7}=1\frac{9}{35}\)
\(\frac{13}{5}x=\frac{44}{35}+\frac{1}{7}\)
\(\frac{13}{5}x=\frac{7}{5}\)
\(x=\frac{7}{5}:\frac{13}{5}\\ x=\frac{7}{13}\)
a) \(\frac{x}{3}-\frac{1}{4}=\frac{-5}{6}\)
\(\Rightarrow\frac{x}{3}=\frac{-5}{6}+\frac{1}{4}\)
\(\Rightarrow\frac{x}{3}=\frac{-7}{12}\)
\(\Rightarrow x=\frac{\left(-7\right).3}{12}\)
\(\Rightarrow x=\frac{-7}{4}\)
Vậy x = \(\frac{-7}{4}\)
b) \(\frac{x+3}{15}=\frac{1}{3}\)
\(\Rightarrow\left(x+3\right).3=15\)
\(\Rightarrow x+3=15:3\)
\(\Rightarrow x+3=5\)
\(\Rightarrow x=5-3\)
\(\Rightarrow x=2\)
Vậy x = 2
c) \(\frac{x-12}{4}=\frac{1}{2}\)
\(\Rightarrow\left(x-12\right).2=4\)
\(\Rightarrow x-12=4:2\)
\(\Rightarrow x-12=2\)
\(\Rightarrow x=2+12\)
\(\Rightarrow x=14\)
Vậy x = 14
d) \(\frac{25}{9}-\frac{12}{13}x=\frac{7}{9}\)
\(\Rightarrow\frac{12}{13}x=\frac{25}{9}-\frac{7}{9}\)
\(\Rightarrow\frac{12}{13}x=2\)
\(\Rightarrow x=2:\frac{12}{13}\)
\(\Rightarrow x=\frac{13}{6}\)
Vậy x = \(\frac{13}{6}\)
_Chúc bạn học tốt_
a)\(\frac{x}{3}-\frac{1}{4}=-\frac{5}{6}\)
\(\frac{x}{3}=-\frac{5}{6}+\frac{1}{4}\)
\(\frac{x}{3}=-\frac{7}{12}\)
\(x=-\frac{7}{12}\times3\)
\(\Rightarrow x=-\frac{7}{4}\)
b) \(\frac{x+3}{15}=\frac{1}{3}\)
\(\frac{x+3}{15\div5}=\frac{1}{3}\)
\(\Rightarrow x=5-3\)
\(\Rightarrow x=2\)
c) \(\frac{x-12}{4}=\frac{1}{2}\)
\(\frac{x-12}{4\div2}=\frac{1}{2}\)
\(x=12+2\)
\(\Rightarrow x=14\)
d) tự làm nhé cũng dễ mà
\(\frac{-2}{3}x+\frac{1}{6}=\frac{2}{3}x-\frac{1}{3}\)
\(\Rightarrow\frac{-2}{3}x-\frac{2}{3}x=\frac{-1}{3}-\frac{1}{6}\)
\(\Rightarrow\frac{-4}{3}x=\frac{-1}{2}\Rightarrow x=\frac{-3}{8}\)